The invention refers to a self-centering feeding device for elongated objects such as logs which shall be processed in a processing machine such as a barker or the like. A feeding device of this kind is described e.g. in the German Pat. No. 1,217,050 issued on Dec. 8, 1966 to B. Valo and comprises a stand, a longitudinal feeder carried by the stand with the aid of a parallel mechanism so as to be vertically adjustable in such a manner that the body of the feeder remains substantially horizontal, and, for controlling the vertical adjustment of the feeder, a mechanical sensor means located above the feeder. The sensor means is defined by a flap which at one end is pivoted to a part which vertically protrudes from the body of the feeder. A rigid stay is at one end pivoted to the flap in half the length thereof and at its other end is pivoted to the stand. The parallel mechanism comprises two crooked link means pivoted to the stand at horizontally spaced locations so that the whole parallel mechanism is elongated in horizontal direction and has a horizontal stationary part. The parallel mechanism is constantly affected by a spring means in such a way that the rest or initial position of the feeder is the highest position thereof, and the rest or initial position of the sensor means is the lowest position thereof. As a result, the gap between the feeder and the sensor means is smallest in the initial position of the device, and the spring means must therefore be relative weak in order that a log which is forwarded on the feeder may be able to separate the feeder and the flap and penetrate into the gap. Consequently, the log cannot be firmly grasped by the centering device so as to be prevented from rotating. The feeding device must be so long as the longest treated logs are expected to be, e.g. 6 m, and an upwardly inclined ramp must be installed at the feed-in end of the feeder due to the fact that the initial or rest position of the feeder is in the elevated position thereof.
In the German patent application Ser. No. P 20 20 27 399 filed on June 4, 1970 by J. Kuhn and published in print on Dec. 9, 1971, as DS No. 2,027,399, a barking machine is described which is provided with a conveyor device comprising two pairs of feeder rollers mounted in a shear mechanism affected by a cylinder-piston-unit. The conveyor device is not able to hold horizontally a log which is unsupported at its rear end.
It is an object of the present invention to provide a feeding device of the kind aforesaid deprived of the above mentioned disadvantages, i.e. a feeding device which (1) firmly grasps the object to prevent its rotations about its longitudinal axis, (2) does not need to be as long as the longest object to be treated, because with the firm grasp at the forward end of the object the rear end thereof may be unsupported, and (3) does not need a feed-in ramp, because the initial position of the feeder is the lowermost position thereof.
The invention is characterized by the features evident from the annexed patent claims. Also the circumstance that the parallel mechanism in the present invention is oriented vertically and has a vertical stationary part contributes to making the device as short as convenient. The firm grasp of the feeder and sensor means on the log also has the advantage that upon use in connection with a barking machine, a special feeder device, conventional in such machines to prevent rotation of the log, may be omitted, because the function thereof is fully taken over by the feeder device of the invention when positioned closely adjacent to the barking machine.